Asteroid 100

Asteroids are rocky and metallic objects that orbit the Sun but are too small
to be considered planets. Asteroids are material left over from the formation of
the solar system.

They are known as minor planets; (in 2006 the International
Astronomical Union reclassified Ceres - see Dwarf
Planets below. Asteroids range in size from Ceres,
which has a diameter of about 1000 km, down to the size of pebbles. Sixteen
asteroids have a diameter of 240 km or greater. They have been found inside
Earth's orbit to beyond Saturn's orbit. Most, however, are contained within a main
belt that exists between the orbits of Mars and Jupiter. Some have orbits
that cross Earth's path and some have even hit the Earth in times past. One of
the best preserved examples is Barringer
Meteor Crater near Winslow, Arizona.

Asteroids are categorised by their position in the solar system.

Main Belt located between Mars and Jupiter approximately 2 to 4 AU from
the Sun. At then end of the 18th century it was realised that, from the
calculated orbits of the known planets, there should have been another
planets between Mars and Jupiter. As a systematic search was being
established, Guiseppe Piazza (1801) discovered Ceres. It was established
that the 'missing planet' had not formed, the gravitational influence of the
massive Jupiter had stirred up the growing small bodies, subjecting them to
frequent collisions and forming the multitude of small bodies we observe
today. Many asteroids from this 'Main Belt' have been ejected from the belt
and collided with other planets and moons of the Solar System.

Near-Earth Asteroids (NEA) which closely approach the Earth

Trojans which are located near to Jupiter's Lagrange points.

Asteroids are given a number indicating the sequence of their discovery.

The image to the left shows the comparative size of the Moon and the first 10
asteroids; Ceres, Pallas, Juno. Vesta, Astraea, Hebe, Iris, Flora, Metis and
Hygiea.

The number of known asteroids (minor planets) is maintained by the Minor
Planet Center, see MPC;
the total was 37,226,817 on 2006 June 13. See MPC
Archive Statistics for the latest figures. The MPC also maintain records of
the known comets.

Dwarf Planets

The International Astronomical Union had a controversial meeting
in Prague in 2006; it reviewed the classification of a planet. On August 24th
2006, the General Assembly "agreed that a 'planet' is defined as a
celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for
its self-gravity to overcome rigid body forces so that it assumes a hydrostatic
equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around
its orbit.

This means that the Solar System consists of eight "planets" Mercury,
Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. A new distinct class of
objects called "dwarf planets" was also decided. It was agreed that
"planets" and "dwarf planets" are two distinct classes of
objects. The first members of the "dwarf planet" category are Ceres,
Pluto and 2003 UB313 (later named - Eris). More "dwarf planets" are
expected to be announced by the IAU in the coming months and years."

The IAU further defined the classification as:

A "planet" is a celestial body that (a) is in
orbit around the Sun, (b) has sufficient mass for its self-gravity to
overcome rigid body forces so that it assumes a hydrostatic equilibrium
(nearly round) shape, and (c) has cleared the neighbourhood around its
orbit.

A "dwarf planet" is a celestial body that (a) is
in orbit around the Sun, (b) has sufficient mass for its self-gravity to
overcome rigid body forces so that it assumes a hydrostatic equilibrium
(nearly round) shape2 , (c) has not cleared the neighbourhood around its
orbit, and (d) is not a satellite.

All other objects3 except satellites orbiting the Sun shall
be referred to collectively as "Small Solar-System Bodies".

Thus Ceres, previously a minor planet or asteroid, was promoted to become a 'dwarf planet' where it
joins Pluto, previously a 'planet'. The IAU further resolved that Pluto is a
"dwarf planet" by the above definition and is recognized as the
prototype of a new category of trans-Neptunian objects.

NASA's DAWN spacecraft is off to visit
Asteroids Vesta and Ceres

NASA launched a spacecraft, Dawn,
on September 27th 2007 with the mission objective of flying to the two giant
asteroids Vesta and Ceres.

Dawn's first stop is Vesta - an asteroid that may implicate ancient
supernovas in the solar system's birth.

Telescopic observations of Vesta and studies of meteorites believed to have
come from Vesta suggest that the asteroid may have been partially molten early
in its history, allowing heavy elements like iron to sink and form a dense core
with a lighter crust on top.

If all goes as planned, Dawn would reach Vesta and enter orbit in the year
2011. Detailed images of Vesta's surface will reveal traces of its molten past,
while spectrometers catalog the minerals and elements that make up its surface.

After orbiting Vesta for about 7 months, Dawn will undertake a manoeuvre
never before attempted: leave the orbit of one distant body, and fly to and
orbit another.

This kind of "asteroid hopping" would be practically impossible if
Dawn used conventional rocket fuel. "We would need one of the largest
rockets that the US has to carry all the propellant," says Marc Rayman,
Project System Engineer for Dawn at JPL. Instead, Dawn uses ion propulsion,
which requires only one-tenth as much propellant. Dawn is planned to arrive at
Ceres in 2015.

I am gradually working my way through collecting images of the Messier 110, Lunar
100 and the Caldwell Objects. I became interested in capturing the movement of
asteroids over hours and days. Asteroids are known by name and a sequential
number indicating the order of their discovery. The first 100 were discovered
between 1801 and 1868.

So why not try to image the first 100 asteroids to be discovered? Capturing asteroid images is one thing I can do on poor
seeing nights in my
light polluted backyard.

My images of the first 100 asteroids are shown below, click on
individual asteroid name to go straight to the image, or scroll down:

Ceres was the first asteroid to be discovered (Guiseppe Piazza, January 1st
1801). Ceres is the largest and most massive Main Belt asteroid (Diameter 590 miles, Orbit period
4.60 years, Distance 178 million miles).

Ceres was discovered by accident. Piazzi was searching for a star listed by Francis
Wollaston as Mayer 87 because it was not in Mayer's zodiacal catalogue in
the position given (it eventually transpired that Wollaston had made a mistake
—the star was in fact Lacaille 87). Instead,
Piazzi found a moving star-like object, which he thought at first was a comet.

Note that Ceres was promoted to a 'dwarf planet' at the IAU Assembly in 2006
- see Dwarf Planets above

Juno is a Main belt asteroid which was discovered in 1804 by Karl L
Harding with a 2" telescope. Juno is the highest Roman Goddessh.
(Dimensions: 290 x 240 x 190 km, Orbit period 4.36 years). Spectroscopic studies
of the Junonian surface conclude that Juno could be the body of origin of
ordinary chondrites, a common group of stony meteorites composed of
iron-containing silicates such as olivine and pyroxene.

Vesta was the fourth asteroid to be discovered (Heinrich Wilhelm Olbers 1807). Vesta is the
third largest Main Belt asteroid (Diameter 285 miles, Orbit period 3.63 years) and the only Main Belt
asteroid visible to the naked eye.

After the discovery of Vesta in 1807, no other asteroids were discovered for
38 years; the next was 5
Astraea.

The same area of sky revisited 9 days later (under
poor seeing conditions) - Asteroid Vesta has moved on.

Astraea is a large Main belt asteroid which was discovered in 1845 by Karl
Ludwig Hencke. (Dimensions 167x123x82 km, Orbit period 4.13 years,
Distance 261.7m km). It has a highly reflective surface and its probable composition
is nickel-iron with magnesium and iron silicates.

Hebe is a very large Main belt asteroid which was discovered in 1847 by Karl
Ludwig Hencke. Hebe is the Greek goddess of youth (Diameter 115 miles, Orbit period
3.78 years). It has a bright surface and composition of nickel-iron metals and
silicate rocks.

Iris is a large Main belt asteroid which was discovered in 1847 by J R Hind
from London, UK. (Dimensions 225x190x190 km, Orbit period 3.68 years,
Distance 131.3million km). It has a highly reflective surface and its probable composition
is nickel-iron with magnesium and iron silicates.

Flora is a bright Main belt asteroid. It is the innermost large asteroid; no
asteroid closer to the sun has a diameter above 25 km. Flora was discovered in 1847 by J R Hind. (Dimensions
145x145x120 km, Orbit period 3.27 years,
Distance 133.9million km). The composition
is a mixture of silicate rocks and nickel-iron metal.

9 Metis is one of the largest Main belt asteroids; it is composed of
silicates and metallic nickel-iron. Metis was discovered by Andrew Graham on April 25, 1848; his only asteroid discovery. It is also the only asteroid to have been discovered as a result of observations from Ireland. Its name comes from the mythological Metis, a Titaness, daughter of Tethys and Oceanus.
Metis is also the name of a satellite of Jupiter. (Size 235 x 195 x 140 km, Orbit period
3.69 years, Distance 241.9 million km).

Hygiea is the fourth largest Main belt asteroid. It was discovered by A. de
Gasparis in 1849 (Diameter 253 miles, Orbit period 5.56 years). Hygiea is
composed of primitive carbonaceous material similar to the chondrite meteorites.
It is the main member of the Hygiea family.

12 Victoria is a large Main belt asteroid. It is probably composed of silicate rock and nickel-iron.
It was discovered by J. R. Hind on September 13, 1850.

Victoria is officially named after the Roman goddess of victory, but the name also honours Queen Victoria of the United Kingdom.
(Diameter 112.8 km, Orbit period 3.57 years, Distance 254.8 million
km).

Irene is a large Main belt asteroid. This stony asteroid contains also
metallic iron-nickel. It was discovered by John Russell Hind in 1851 (Diameter
113 miles, Orbit period 4.16 years, Distance 133 million miles).

Eunomia is a very large inner Main belt asteroid. It is the largest of the
stony (S-type) asteroids. It was discovered by A de Gasparis in 1851 (Diameter
330 km, Orbit period 4.30 years, Distance 281.7 million km.)

Psyche is a very large Main belt asteroid. It is the largest of the metallic
(M-type) asteroids. It was discovered by Annibale de Gasparis in 1852 (Diameter
280 x 230 x 190 km, Orbit period 4.99 years, Distance 357.3 million km.)

17 Thetis is a large Main belt asteroid. It is a S-type asteroid so it has a
relatively bright silicate surface. It was discovered by John Russell Hind in
1852 (Diameter 90 km, Orbit period 3.88 years, Distance 243.8 million km).

Melopmene is a large bright Main belt asteroid. It is composed of silicates
and metals. It was discovered by John Russell Hind in 1852 (Diameter 93 x 78 miles, Orbit period
3.48 years, Distance 129 million miles).

Fortuna is one of the largest main belt asteroids. It has a
composition similar to 1 Ceres; a darkly coloured surface and composition of
primitive carbonates. It was discovered by John Russell Hinds in London in 1852 (Diameter
215 km, Orbit period 3.81 years, Distance 164.2 million km).

30 Urania was discovered by J R Hind on July 22nd 1854; it is named after
Urania, the Greek Muse of Astronomy. It is a large Main belt asteroid
(Diameter 100.15 km, Orbit period 3.64 years, Distance 173.2 million km).

31 Euphrosyne was discovered by James Ferguson in 1854; it is named after
Euphrosyne, one of the Charities in Greek mythology. Amphitride is one of the
kargest Main belt asteroids
(Diameter 255.9 km, Orbit period 5.59 years, Distance 389.2 million km.).

32 Pomona is a main belt asteroid. Pomona was discovered by H. Goldschmidt on October 26, 1854. It is named after Pomona, the Roman goddess of fruit trees.
(Diameter 80.8 km, Orbit period 4.16 years, Distance 228 million km).

34 Circe is a large, very dark Main Belt asteroid. It was discovered by J Chacomac in 1854; it is named after
Circe, a goddess in the Greek mythology. (Diameter 113.5 km, Orbit period
4.40 years, Distance) 341.1 million km.)

35 Leukothea is a large dark Main Belt asteroid. It was discovered by R.
Luther on April 19th 1855; it is named after Leukothea, a sea goddess in the Greek mythology. (Diameter
103.1 km, Orbit period 5.17 years, Distance) 384.1 million km.)

36 Atalante is a large, dark Main Belt asteroid. It was discovered by H
Goldschmidt in 1855; it is named after Atalante, a horeine in the Greek mythology. (Diameter
105.6 km, Orbit period 4.55 years, Distance 230.1 million km.)

37 Fides is a large Main Belt asteroid. It was discovered by R Luther in
1855; it is named after Fides, the Roman goddess of loyalty. (Diameter
108.3 km, Orbit period 4.29 years, Distance 203.1 million km.)

38 Leda was discovered by J Chacomac in 1856; it is named after Leda,
the mother of Helen of Troy in Greek mythology. Leda is a large, dark Main belt asteroid
(Diameter 115.9 km, Orbit period 4.54 years, Distance 1.49 million km).

39 Laetitia was discovered by J Chacornac in 1856; it is named after
Laetitia, a Roman goddess of gaiey. It is a Main belt asteroid
(Diameter 149.5 km, Orbit period 4.61 years, Distance 254 million km).

40 Harmonia is a large main belt asteroid. It was discovered by H. Goldschmidt on March 31, 1856 and named after Harmonia, the Greek goddess of harmony. The name was chosen to mark the end of the Crimean War.
(Diameter 107.6 km, Orbit period 3.41 years, Distance 230.6 million km).

41 Daphne is a large main belt asteroid. This dark-surfaced body is likely
composed of primitive carbonaceous chondrites. It was discovered by H. Goldschmidt on
May 22nd, 1856 and named after Daphne, the nymph in Greek mythology who was
turned into a laurel tree. (Diameter 174 km, Orbit period 4.6 years, Distance
374.3 million km).

42 Isis is a large main belt asteroid. It was discovered by N R Pogson on May
23rd, 1856 and named after Isis, the Greek name of an Egyptian goddess.
(Diameter 100.2 km, Orbit period 3.82 years, Distance 301.3 million km).

43 Ariadne is a large, bright, main belt asteroid. It was discovered by N R Pogson on
April 15th, 1857 and named after the Greek heroine Ariadne.
(Diameter 95 x 60 x 50 km, Orbit period 3.27 years, Distance 220.8 million km).

44 Nysa is a quite large and very bright main belt asteroid. It is the
brightest member of the Nysa asteroid family. It is classified as a rare class E
asteroid. It was discovered by H Goldschmidt on May 27th, 1857 and named after
Nysa in Greek mythology.
(Diameter 70.6 km, Orbit period 3.77 years, Distance 183.3 million km).

45 Eugenia is a large Main belt asteroid. It is famed as one of the
first asteroids to be found to have a moon orbiting it. Eugenia was discovered
in 1857 by Hermann Goldschmidt. (Diameter 134 miles, Orbit period
4.49years, Distance 150 million miles).

Hestia is a large, dark Main belt asteroid: it is also the primary body of
the Hestia asteroid clump. It was discovered by N R Pogson in 1857 (Diameter
124.1 km, Orbit period 4.02 years, Distance 194.5 million
km).

47 Aglaja is a large and dark Main belt asteroids. Kalyso was discovered
on September 15th by R. Luther; it is named after Aglaea, one of the Charities
in Greek Mythology. (Diameter 127 km, Orbit period 4.89 years, Distance
360.6 million km).

49 Pales a large, dark Main belt asteroid. Pales was discovered on
September 19th 1857 by Hermann Goldschmidt. Pales is the goddess of
shepherds in Greek mythology. (Diameter 149.8 km, Orbit period 5.42years, Distance
344.8 million km).

50 Virginia is a large, very dark Main belt asteroid. It was discovered by J. Ferguson on October 4, 1857. R. Luther found it independently on October 19, and his discovery was announced first. The reason for Virginia's name is not known.
(Diameter 99.8 km, Orbit period 4.31 years, Distance 373.5 million km).

52 Europa a large, dark Main belt asteroid. Pales was discovered on
February 4th 1858 by Hermann Goldschmidt. Europa is the seventh largest
asteroid and contains a little less than 2% of the mass of the main belt. (Diameter
289 km, Orbit period 5.46 years, Distance 377.9 million km).

55 Pandora is a quite large and very bright Main belt asteroid.
Pandora was discovered by G. Searle on September 10, 1858. It was his first and
only asteroid discovery. It is named after Pandora, the first woman in Greek
mythology. (Diameter 66.7 km, Orbit period 4.58years, Distance 216.0 million km).

56 Melete is a large dark Main belt asteroid. Melete was discovered by
H. Goldschmidt on September 9th 1857. Melete is an unusual class P asteroid,
composition probably organic rich silicates, carbon and anhydrous silicates with
possible internal water ice. It is named after Melete, the Muse of meditation in Greek
mythology. (Diameter 113.2 km, Orbit period 4.18 years, Distance 350.9 million km).

57 Mnemosyne is a large Main belt asteroid. Mnemosyne was discovered by
R. Luther on September 22nd 1859. Melete is an S-type asteroid. It is named after
Mnemosyne, a Titaness in Greek
mythology. (Diameter 112.6 km, Orbit period 5.59 years, Distance 376.4 million km).

58 Concordia is a quite large Main belt asteroid. Concordia was discovered by
R. Luther on March 24th 1860. Concordia is a class C asteroid, its surface is
dark and it's composition is likely to be carbonaceous. It is named after
Concordia, the Roman goddess of harmony. (Diameter 93.4 km, Orbit period
4.44 years, Distance 252.9 million km).

59 Elpis is a very large Main belt asteroid. Concordia was discovered byJ.
Chacomac on September 12th 1860. Elpis is a class C asteroid, its surface is
dark and it's composition is carbonaceous. It is named after Elpis, a
personification of hope. (Diameter 164.8 km, Orbit period 4.47 years, Distance
371.7 million km).

60 Echo is a quite large Main belt asteroid. Echo was discovered by
James Ferguson on September 14th 1860. Concordia is a class S asteroid, its
surface is bright in color and it is probably a mixture of iron-nickel metals
and silicate rock. It is named after Echo, a nymph in Greek mythology. (Diameter
60.2 km, Orbit period 3.70 years, Distance 197.5 million km).

61 Danae is a quite large, rocky Main belt asteroid. Echo was discovered by
H Goldschmidt on September 9th 1860. It is named after Danae, the mother of
Perseus, in Greek mythology. (Diameter 82.0 km, Orbit period 5.15 years, Distance
359.0 million km).

62 Erato is a large and dark, probably carbonaceous main belt asteroid. It is a member of the Themis asteroid family. Erato is the first asteroid to have been credited with co-discoverers, Oskar Lesser and Wilhelm Forster, who discovered it on September 14, 1860. It was their first and only asteroid discovery. It is named after Erato, the Muse of lyric poetry in Greek mythology. (Diameter
95.4 km, Orbit period 5.51 years, Distance 395.7 million km).

63 Ausonia is a large main belt asteroid. It was discovered it on
February 10th, 1861 by A de Gasparis. Ausonia is an alternative name
for Italy. (Diameter 103.1 km, Orbit period 3.71 years, Distance 234.7 million km).

64 Angelina is a quite large Main belt asteroid. It belongs to the less common spectral class E. It was discovered on March 4, 1861 by a prolific comet discoverer, E. W. Tempel. It was first of his five asteroid discoveries.
(Diameter 85 - 190 km, Orbit period 4.39 years, Distance 232.9 million km).

65 Cybele is one of the largest asteroids in the Main belt. Cybele was discovered by
Ernst Tempel on March 8th 1861. Cybele is a class C asteroid, its surface is
dark and it's composition is likely to be carbonaceous. It is named after Cybele,
the earth goddess. (Diameter 237.3 km, Orbit period 6.73 years, Distance
423.1 million km).

66 Maja is a dark large asteroid in the Main belt. Maja was discovered by
Horace Tuttle on April 9th 1861. It is named after Maia, one of the Pleiades in
Greek mythology. (Diameter 72.8 km, Orbit period 4.30 years, Distance
407.8 million km).

67 Asia is a bright Main belt asteroid. Asia was discovered by Norman
Pogson on April 17th 1861. It is named after Asia, a Titaness in Greek
mythology, but also after the continent, because the asteroid was the
first to be discovered from Asia. (Diameter 58.1 km, Orbit period 3.77 years, Distance
281.6 million km).

68 Leto is a large Main Belt asteroid. Cybele was discovered by Robert
Luther on April 29, 1861. It is named after Leto,
the mother of Apollo and Artemis in Greek mythology. (Diameter 122.6 km, Orbit period
4.65 years, Distance 220.8 million km).

75 Eurydike is a Main belt asteroid. It has an M-type spectrum
and a relatively high albedo and may be rich in nickel-iron. Eurydike was discovered
by C H F Peters on September 22nd 1862. (Diameter 55.7 km, Orbit period 4.38 years, Distance
150.2 million km).

76 Freia is a very large Main Belt asteroid. It orbits in the
outer part of the asteroid belt and is classified as a Cybele asteroid. Freia was discovered
by Heinrich d'Arrest on October 21st. 1862. (Diameter 183.7 km, Orbit period
6.31 years, Distance 366.2 million km).

77 Frigga is a very large, M-type, possibly metallic Main Belt asteroid.
Frigga was discovered
by C H F Peters on November 12th. 1862. (Diameter 69.2, Orbit period 4.36 years, Distance
354.3 million km).

79 Eurynome is a large, bright Main belt asteroid. It is
composed of nickel-iron metals and silicate rocks. Eurynome was discovered
by J.C. Watson on September 14th 1863. (Diameter 66.5 km, Orbit period 3.82
years, Distance 211.3 million km).

Sappho is a quite large main belt asteroid. It was discovered by Norman Pogson on May 2, 1864 and is named after Sappho, the Greek poet.
(Diameter 78.4 km, Orbit period 3.48 years, Distance 278.5 million km).

81 Terpsichore is a large and very dark main belt asteroid. It has most likely a very primitive carbonaceous composition. It was found by the prolific comet discoverer Ernst Tempel on September 30, 1864. It is named after Terpsichore, the Muse of dance in Greek mythology.
(Diameter 119.1 km, Orbit period 4.82 years, Distance 338.5 million km).

83 Beatrix

Beatrix is a quite large asteroid orbiting in the inner part of the main belt asteroid. It was discovered by
Annibale de Gasparis in April 1865. (Diameter 81.4 km, Orbit period 3.79 years, Distance
239.9 million
km).

Io is a large and dark-colored Main belt asteroid. It is probably a primitive body composed of carbonates. Like 70 Panopaea it orbits within the Eunomia asteroid family but it is most likely not related to the shattered parent body. It was discovered by C. H. F. Peters on September 19, 1865 and named after Io, a lover of Zeus in Greek mythology. Io is also the name of the volcanic satellite of Jupiter.
(Diameter 154.8 km, Orbit period 4.32 years, Distance 350.8 million km).

87 Sylvia is one of the largest Main belt asteroids; discovered by N R Pogson
in 1866. It is a member of the Cybele group located beyond the core of the belt.
Sylvia is remarkable for being the first known asteroid to possess more than one
moon. (Diameter 385 x 265 x 10 km, Orbit period 6.52 years, Distance 413.3
million km).

88 Thisbe is one of the largest main belt asteroids. It was discovered
by C. H. F. Peters on June 15, 1866 and named after Thisbe, heroine of a Roman
fable. An occultation of a star by Thisbe was observed on October 7, 1981.
Results from the occultation indicate a larger than expected diameter of 232
km. (Diameter 232.0 km, Orbit period 4.60 years, Distance 265.2 million km).

89 Julia is a large main belt asteroid. It is likely composed of
silicate rock and nickel-iron metals. It was discovered by a French astronomer
Édouard Stephan on August 6, 1866. It was first of his two asteroid
discoveries; the other was 91 Aegina. (Diameter 151.5 km, Orbit period
4.07years, Distance 197.4 million km).

Antiope is a Main belt asteroid. It was discovered by R Luther in 1866.
In 2000, using adaptive optics at the Keck Telescope on Mauna Kea it was discovered that Antiope is in fact a double asteroid. It consists of two individual bodies (the "secondary" is designated S/2000 (90) 1), each about 110±16 km across, separated by only 170 kilometers, orbiting around a common
centre. (Diameter 110 +/- 16 km each component, Orbit period 5.61 years, Distance
331.1 million
km). More recent observations with the European Southern Observatory’s 8-metre
Very Large Telescope have taken the observations to the next level. The
observatory has helped to reveal 90 Antiope as two egg-shaped piles of rubble
orbiting one another. Each asteroid is roughly 86 km (53 miles) in diameter, and
they’re separated by only 171 kilometres (106 miles).

Aegina is a Main belt asteroid. It was discovered by Edouard Jean-Marie
Stephan on November 4th 1866. Its surface coloring is very dark and the
asteroid has probably a primitive carbonaceous composition. The asteroid's name
comes from Angina, a Greek mythological figure associated with the island of the
same name. (Diameter 109.8 km, Orbit period 4.71 years, Distance 289.0 million
km).

92 Undina is a large main belt asteroid. It has an unusually high
albedo and an M-type spectrum. It was discovered by C H F Peters on July 7th, 1867.
Undina is a member of the Veritas asteroid family, which formed some eight
million years ago. (Diameter 126.4 km, Orbit period 5.70 years, Distance
368.8 million km).

93 Minerva is a large main belt asteroid. It is probably a C-type
asteroid of carbonaceous composition. It was discovered by J C Watson on August
24, 1867. Minerva was the goddess of wisdom. (Diameter 146 km, Orbit period
4.57years, Distance 462.4 million km).

Aurora is one of the largest Main belt asteroids. It is very dark, darker
than soot. It was discovered by J C Watson in 1867; Aurora is the Roman goddess
of the dawn. (Diameter 127 miles, Orbit period 5.63 years).

95 Arethusa

95 Arethusa is a large main belt asteroid. It is of carbonaceous
composition. It was discovered by Robert Luther on November 23, 1867. There are
several Arethusas in Greek Mythology. (Diameter 136 km, Orbit period
5.38 years, Distance 299.6 million km).

Aegle is a very large main belt asteroid. It has a dark surface and is
probably a primitive carbonaceous composition. It was discovered by Jerome
Coggia in 1868. (Diameter 127 miles, Orbit period 5.63 years, Distance 407
million km).

98 Ianthe is a large main belt asteroid. It is very dak and is composed
of carboantes. It was discovered by C H F Peters on Aptil 18th 1868
from Clinton, New York. (Diameter 104.5 km, Orbit period 4.40 years, Distance
274.6 million km).

Below is an animation of 98 Ianthe in Triangulum. It shows the movement of
the asteroid against the star background over 115 minutes. This project was only
taken as we had a super clear night BUT a full moon. Quality of images is not
good because of adjacent moon but it was something to try.

100 Hekate is a large main belt asteroid. It orbits in the same region
of space as the Hygiea asteroid family, however it is actually an unrelated
interloper. Its albedo of 0.19 is too high, and it is of the wrong spectral
class to be part of the dark carbonaceous Hygiea family. It was discovered by J
C Watson in 1868. (Diameter 89 km, Orbit period 5.44 years, Distance 396.9 million km).

Asteroids can make a big hole in the ground if they happen to collide with
the Earth. Meteor Crater, 35 miles east of Flagstaff, Arizona, is a gigantic
hole in the middle of the high desert. The crater is nearly a mile wide and 570
feet deep and was formed some 50,000 years ago. 30 tons of meteoric iron have
been found within 10 miles of the crater. Recent theories suggest that the large
meteorite fragmented before impact as it passed through the Earth's atmosphere.

Meteor crater is worth a visit if you are in Arizona: the scale of the impact
can only be imagined if you stand on the rim. No access is allowed down into the
crater, which is a protected area, but walks along the rim are in managed
groups.

If you get that way then the Lowell Observatory is in nearby Flagstaff where
evening viewing through Lowell's telescope is provided - see if you can see the
canals on Mars! More details on my Mars page; see Lowell
Observatory.

Much of our understanding about asteroids comes from examining pieces of
space debris that fall to the surface of Earth. Asteroids that are on a
collision course with Earth are called meteoroids. When a meteoroid strikes our
atmosphere at high velocity, friction causes this chunk of space matter to
incinerate in a streak of light known as a meteor. If the meteoroid does not
burn up completely, what's left strikes Earth's surface and is called a
meteorite.

Of all the meteorites examined, 92.8 percent are composed of silicate
(stone), and 5.7 percent are composed of iron and nickel; the rest are a mixture
of the three materials.

Pieces
of meteorites are available for purchase; I purchased a piece of the 12th
Feb 1947 Sikhote Alin meteorite. This is an iron-nickel coarsest octahedrite
which fell in Siberia. My piece weighs only 24.5gm but adds much interest to
those who see an asteroid through the telescope and can then touch a specimen
from a similar object.

My first meteorite was purchased at a Leeds Astromeet from York
Meteorites. I have purchased further meteorites from sites on

Reference

O.
Richard Norton's book, Rocks from Space, is an attractive and easily read
book giving an introduction to all hazards arriving on Earth from Space -
asteroids, comets and meteorites and their impact on the surface.

The book also covers the 'Meteorite Hunters', lists the authenticated impact
craters worldwide and provides a useful glossary.